WiFi technology is one of the basic building blocks of smart cities, as it is required for integrating advanced networked sensors with physical devices to realize the main goal of the Internet of Things (IoT). This paper contributes to answering the question of which WiFi standard is the most practical to be deployed outdoors in a smart city by testing the data transfer throughput performance of three WiFi standards, namely, IEEE 802.11ax, 802.11ac, and 802.11n. Two configurations are investigated. One considers a single-user connection from a WiFi node to an Ethernet-wired destination, whereas the other considers a relayed connection through an access point (AP) between two WiFi nodes. The two configurations examine both the reliable transfer mode using the transmission control protocol (TCP) and the unreliable mode using the user datagram protocol (UDP). The measurements are conducted in an outdoor environment mimicking a smart city setting with a relatively wide range of distances. Our results show that the throughput performance of both IEEE 802.11ax and IEEE 802.11ac is significantly higher than IEEE 802.11n over the entire distance range. Surprisingly, it is found that the more recent IEEE 802.11ax can outperform the older IEEE 802.11ac only over relatively short distances, while IEEE 802.11ac significantly excels beyond some transmitter-receiver distance.